CULTIVATION IN THE OPEN AIR 



Corms and bulbs are kept down in the soil in this way by means 

 of special roots called " contractile." These are the thickisli ringed 

 roots referred to and shown in the sketches (see Figs. 3, 6, 14, 19). 

 It appears that when the new corms or bulbs have developed fairly 

 well, these contractile roots have already pushed their way deeper 

 into the soil, lower than the older corms. In due course they begin 

 to contract, and in this way they exert sufficient force to pull down 

 the new corms to a lower level, perhaps even lower than the parents 

 were the previous season. The marvellous power possessed by these 

 contractile roots is one of the most mysterious functions of bulbous 

 plants, and it is only another instance showing how carefully and 

 beautifully everything was thought of " at the beginning." 



CULTIVATION IN THE OPEN AIR 



SOILS AND COMPOSTS 



If this volume were confined to the consideration of hardy plants 

 alone, it would be a comparatively simple matter dealing with the 

 soil. But as we are dealing not only with hardy plants that may be 

 always grown in the open air, but also with those that must be 

 sheltered in a greenhouse and hothouse and are often grown in pots, 

 it becomes necessary to take a wider view of the subject, treating 

 the outdoor cultivation and the indoor separately. 



Generally speaking, most of the hardy bulbous, tuberous, and 

 rhizomatous plants (of which a hst is given at p. 32) will flourish 

 in any well-drained, deeply dug or trenched and well-manured 

 garden soil. Indeed, some like the tuberous Sunflowers, the 

 Bocconias, the Aconites, Doronicums, Hemerocallis, etc., will grow in 

 any but the very worst sour and swampy soil, so vigorous is the 

 action of their roots. Advantage may be taken of such coarse or 

 free-growing plants to improve soil that is generally regarded as 

 poor and infertile. They will find not only nourishment in it, but 

 owing to the action of .their rapidly spreading roots, they bring 

 about a much better condition of the impoverished soil after a 

 season or two of growth. 



No one, however, wishes to be saddled with poor and hungry or 

 swampy soil if better can be had. The ideal garden soil is one 

 called loam — a fairly well-balanced mixture of clay and sand, with 

 a fair amount of humus (or decayed organic material), and a certain 



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